# Decoding Heat-Shock Responses in Vitis vinifera L. by Metabolic, VOC, and Physiological Profiling: Toward the Identification of Volatile and Metabolic Biomarkers

## TL;DR

This study identifies potential biomarkers for heat stress in grapevines using metabolic and volatile compound profiling, aiming to improve heat tolerance in breeding.

## Contribution

The study introduces new volatile and metabolic biomarkers for heat stress in grapevines, validated both in controlled and field conditions.

## Key findings

- 6-methyl-5-hepten-2-one and benzenic compounds like 2-phenyl-2-propanol are candidate heat stress markers.
- Metabolites MEP-cPP and guanosine accumulate in heat-sensitive grapevine genotypes.
- Biomarkers were validated in field conditions, offering tools for breeding heat-tolerant grapevines.

## Abstract

Grapevine (Vitis spp.) is a crop of
major economic
importance in Europe. Rising temperatures and extreme weather events
reduce the yield and alter berry composition, affecting wine quality.
Despite advances in vineyard management, mechanisms underlying grapevine
thermotolerance remain poorly understood. To fill this gap, we combined
physiological and volatile organic compound profiling and untargeted
metabolomics. Selected genotypes from a 'Rhine Riesling'
× 'Cabernet
Sauvignon' progeny were exposed to a 3 h heat shock at 40 and
43 °C
under controlled conditions. At 43 °C, genotypes were heat stressed,
with a significant chlorophyll fluorescence decrease and modulation
of leaf transpiration and metabolism. VOC analysis highlighted 6-methyl-5-hepten-2-one
as a candidate heat stress marker, as well as benzenic compounds (i.e.,
2-phenyl-2-propanol). Untargeted metabolite profiling revealed several
candidate heat-stress biomarkers; notably, the hypothesized 2-C-methyl-d-erythritol 2,4-cyclodiphosphate (MEP-cPP)
and guanosine accumulated preferentially in susceptible genotypes.
Both markers were validated in the field, providing candidate molecular
tools for breeding heat-tolerant grapevines.